Laser welding of galvanized steel sheets, that is, steel sheets that have a thin coating of zinc for corrosion protection are well known to those skilled in the art. A problem associated with laser welding steel sheets that have a zinc coating is that the zinc vaporizes during laser welding creating zinc vapors. These zinc vapors can cause porosity in the weld nugget with reduces the integrity and quality of the weld.
The zinc vapor problem associated with laser welding is known and various solutions have been proposed to deal with this problem as described in the U.S. Pat. Nos. 4,642,446 to Pennington; 4,916,284 to Petrick; 4,682,002 to Delle Piane et al.; and to 4,745,257 to Rito et al. In Pennington the zinc coating is removed and replaced by a nickel-base coating over selected areas where laser welding is to take place. In Rito et al. and Delle Piane et al. spacers are used to space the sheets to be welded thereby providing a path for the escape of zinc vapors. In Petrick the parts to be welded are shaped to provide a path for the escape of zinc vapors.